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Discovery and analysis of a ULX nebula in NGC 3521★

López, KM; Jonker, PG; Heida, M; Torres, MAP; Roberts, TP; Walton, DJ; Moon, D-S; Harrison, FA

Discovery and analysis of a ULX nebula in NGC 3521★ Thumbnail


KM López

PG Jonker

M Heida

MAP Torres

DJ Walton

D-S Moon

FA Harrison


We present Very Large Telescope/X-shooter and Chandra X-ray observatory/ACIS observations of the ULX [SST2011] J110545.62+000016.2 in the galaxy NGC 3521. The source identified as a candidate near-infrared counterpart to the ULX in our previous study shows an emission line spectrum of numerous recombination and forbidden lines in the visible and near-infrared spectral regime. The emission from the candidate counterpart is spatially extended (∼34 pc) and appears to be connected with an adjacent H II region, located ∼138 pc to the NE. The measured velocities of the emission lines confirm that both the candidate counterpart and H II region reside in NGC 3521. The intensity ratios of the emission lines from the ULX counterpart show that the line emission originates from the combined effect of shock and photoionisation of low metallicity (12 + log  (O/H) = 8.19 ± 0.11) gas. Unfortunately, there is no identifiable spectral signature directly related to the photosphere of the mass-donor star in our spectrum. From the archival Chandra data, we derive the X-ray luminosity of the source in the 0.3–7 keV range to be (1.9 ± 0.8) × 1040 erg cm−2 s−1, almost a factor of four higher than what is previously reported.


López, K., Jonker, P., Heida, M., Torres, M., Roberts, T., Walton, D., …Harrison, F. (2019). Discovery and analysis of a ULX nebula in NGC 3521★. Monthly Notices of the Royal Astronomical Society, 489(1), 1249-1264.

Journal Article Type Article
Acceptance Date Jul 29, 2019
Online Publication Date Aug 5, 2019
Publication Date Oct 31, 2019
Deposit Date Aug 13, 2019
Publicly Available Date Aug 13, 2019
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 489
Issue 1
Pages 1249-1264
Related Public URLs


Accepted Journal Article (3.4 Mb)

Copyright Statement
This article has been accepted for publication in the Monthly notices of the Royal Astronomical Society ©: 2019 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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